The present invention relates to air-drying or semi-drying alkyd paints. More particularly, it relates to high-solids alkyd paints.
Environmental concern during the last years has led to a considerable demand for paints with a higher solids content. As used herein, "high-solids" refers to coatings with at most about 250 g/l of volatile organic compounds (VOCs).
High solids paints have long been known. However, historically they did not offer the same level of performance as presently known paints which have a higher solvent content. There is thus a demand for high-solids paints which perform at least as good as those everyone is currently using which have high VOCs.
The concept of reactive diluent is known in the art of high-solids paints (see e.g. Chapter 6 in High Solids Alkyd Resins, K. Holmberg, Dekker, 1987). European patent EP-357128-A discloses an alkyd-type reactive diluent. European patent EP-301345-A discloses a polyesterurethane containing ether groups and prepared from an isocyanate containing at least one copolymerisable double or triple carbon-carbon bond, used as a reactive diluent for oxidatively drying binders. The U.S. Pat. No. 4609706 discloses the use of hydroxy-functional oligomer reacted with a compound containing both one ethylenic unsaturation and one isocyanate functionality as reactive diluent for drying oil modified alkyd resin.
However, the performances obtained are insufficient, and there is a need in the art for high-solids air-drying or semi-drying paints having better properties.
It is an object of this invention to provide air-drying or semi-ring alkyd paints of higher solids content.
Another object of the invention is to provide air-drying or semi-drying alkyd paints of higher hiding power.
Still another object of the invention is to provide air-drying or semi-drying alkyd paints having improved drying properties.
Yet another object is to provide air-drying or semi-drying alkyd paints which can be applied in thicker layers without sagging.
A further object is to provide air-drying or semi-drying alkyd paints having an improved balance of the above objects.
Still a further object of the invention is to provide a reactive diluent that can be used in combination with conventional air-drying or semi-drying long-oil or medium-oil alkyd resins to formulate high-solids air-drying or semi-drying alkyd paints meeting one or more of the above objects.